1. Field of the Invention
The present invention relates generally to jumbo-size picture display devices and, more particularly, is directed to a jumbo-size picture display device in which a number of trios, each being formed of red, green and blue fluorescent segments, are arranged in an X-Y matrix-fashion.
2. Description of Prior Art
A jumbo-size picture display device for displaying a large color picture, for example, a jumbo-size color picture is represented, for example, in FIG. 1.
As shown in FIG. 1, for example, red, green and blue fluorescent segments R, G and B are formed as a set, i.e., trio. A fluorescent display cell 41 is formed in which 16 trios of fluorescent segments R, G and B are arranged on its fluorescent screen in, for example, 2 rows and 8 columns. A plurality of fluorescent display cells 41 are arranged in each of the vertical direction Y and in the horizontal direction X, thereby forming a jumbo-size picture display device 40. In this jumbo-size picture display device 40, the respective fluorescent segments are driven in response to display data to display a color visual image of jumbo-size.
Each of the fluorescent display cells 41 forming the jumbo-size picture display device 40 is constructed as follows:
The fluorescent display cell 41, as shown in FIG. 2, includes a front panel 42, a rear panel 43 and side plates 44 which are bonded by frit glass 45 to form a flat glass housing 46. Within this flat glass housing 46, an electron beam control mechanism is provided in an opposing relation to a fluorescent screen 47 that is formed on the inner surface of the front panel 42 by aligning thereon red, green and blue fluorescent segments R, G and B. This electron beam control mechanism, denoted by reference numeral 48 in FIG. 2, includes at least a cathode and first and second grids to urge an electron beam to impinge upon the red, green and blue segment trios R, G and B. Lead wires 49, which apply a low voltage to the electron beam control mechanism 48, are led-out to the outside of the housing 46 via the frit glass 45 between the rear panel 43 and the side plate 44. A high voltage (anode voltage) is applied to the fluorescent screen 47.
In the jumbo-size picture display device 40 in which a number of fluorescent display cells 41, each having the fluorescent screen with the red, green and blue fluorescent segments R, G and B, are arranged in the X-Y matrix form, at least irregular color temperature between the fluorescent display cells 41 must be reduced in order to obtain a jumbo-size picture of excellent image quality and of high definition.
More specifically, in order to measure a color temperature, a white color is displayed in each of the fluorescent display cells 41. As shown, in FIG. 3, certain of the fluorescent display cells 41a and 41b although they display the same color white, the same color white appears pale and yellowish due to the increase and decrease of the color temperature, thus giving rise to irregularities of the displayed white colors. This irregularity of the displayed white color due to irregularity of the color temperature between the fluorescent display cells considerably degrades the quality of the reproduced picture.
Further, the color temperature with respect to a white color is standardized at 9300.degree..+-.2000.degree. Kl, and a fluorescent display cell which has a white color temperature which is outside the standardization temperature must be considered a failed or unabled fluorescent display cell.
Furthermore, in the prior-art jumbo-size picture display device 40, in order to reduce irregularities of the color temperature between the fluorescent display cells, the accuracy of the assembly parts of the electrodes and the accuracy in the assembly-process must be increased. Further, irregularities in the manufacturing-process of the fluorescent screen (film thickness, metal back layer, et cetera) must be reduced.